CVE-2020-36838

The Facebook Chat Plugin for WordPress is vulnerable to authorization bypass due to a missing capability check on the wp_ajax_update_options function in versions up to, and including, 1.5. This flaw makes it possible for low-level authenticated attackers to connect their own Facebook Messenger account to any site running the vulnerable plugin and engage in chats with site visitors on affected sites.

Weakness

The product does not restrict or incorrectly restricts access to a resource from an unauthorized actor.

Extended Description

Access control involves the use of several protection mechanisms such as:

When any mechanism is not applied or otherwise fails, attackers can compromise the security of the product by gaining privileges, reading sensitive information, executing commands, evading detection, etc. There are two distinct behaviors that can introduce access control weaknesses:

Potential Mitigations

• Compartmentalize the system to have “safe” areas where trust boundaries can be unambiguously drawn. Do not allow sensitive data to go outside of the trust boundary and always be careful when interfacing with a compartment outside of the safe area.
• Ensure that appropriate compartmentalization is built into the system design, and the compartmentalization allows for and reinforces privilege separation functionality. Architects and designers should rely on the principle of least privilege to decide the appropriate time to use privileges and the time to drop privileges.

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/19.html
• https://cwe.mitre.org/data/definitions/441.html
• https://cwe.mitre.org/data/definitions/478.html
• https://cwe.mitre.org/data/definitions/479.html
• https://cwe.mitre.org/data/definitions/502.html
• https://cwe.mitre.org/data/definitions/503.html
• https://cwe.mitre.org/data/definitions/536.html
• https://cwe.mitre.org/data/definitions/546.html
• https://cwe.mitre.org/data/definitions/550.html
• https://cwe.mitre.org/data/definitions/551.html
• https://cwe.mitre.org/data/definitions/552.html
• https://cwe.mitre.org/data/definitions/556.html
• https://cwe.mitre.org/data/definitions/558.html
• https://cwe.mitre.org/data/definitions/562.html
• https://cwe.mitre.org/data/definitions/563.html
• https://cwe.mitre.org/data/definitions/564.html
• https://cwe.mitre.org/data/definitions/578.html

References

• https://www.wordfence.com/blog/2020/08/the-official-facebook-chat-plugin-created-vector-for-social-engineering-attacks/
• https://www.wordfence.com/threat-intel/vulnerabilities/id/36ae4183-5fa7-484c-b858-5df10ae3d3f2?source=cve